1. Field of the Invention
This invention relates to a control system of a vehicle.
2. Description of the Related Art
In vehicles, a variety of electronic control units (ECUs) are installed to electronically control vehicle-mounted devices.
For example, there are installed an engine ECU for controlling an engine, a transmission ECU for controlling a transmission, a brake-related ECU for performing control according to brake operation, and braking-force control in anti-lock braking system, traction control, etc., a drive-related ECU for controlling distribution of drive force among wheels, a body-related ECU for controlling body-related devices such as doors, windows, windshield wipers, lights and like, etc.
Such ECUs, etc. are connected by a communication path allowing them to communicate with each other, such as an in-vehicle LAN according to the CAN (controller area network) standard (see Japanese Patent Publication 2005-238950, for example).
In such configuration, when a specified ECU, for example, the transmission ECU receives a signal indicating that the ignition switch is in “on” position, the transmission ECU sends a control start signal to pertinent ECUs.
Generally, when the ignition switch is shifted to “off” position, the transmission ECU sends a control stop signal to the pertinent ECUs so that they terminate control.
In such configuration, however, if, while the vehicle is moving, the ignition switch is shifted to the “off” position by erroneous operation, or a control stop signal is erroneously sent to the pertinent ECUs due to failure of the transmission ECU that receives a signal indicating whether the ignition switch is on or off, or a defect or the like of the communication path connecting the ECUs does not allow normal communications among the ECUs, there is caused a problem that the ECUs terminate control while the vehicle is moving.
This is undesirable, particularly because stop of control over braking systems such as an ABS may impair running safety.